1. Field of the Invention
The present invention generally relates to an image forming apparatus such as a copier, a printer, a facsimile machine, or a multifunction machine including at least two of those functions.
2. Discussion of the Background Art
Currently, image forming apparatuses, such as copiers, printers, facsimile machines, or multifunction machines including at least two of those functions, etc., often provide a sheet discharge space inside a housing thereof to make them compact. In such image forming apparatuses, which are called “housing-internal discharge type image forming apparatuses”, sheets of recording media on which images are formed are not discharged onto a discharge tray projecting from a side of the image forming apparatuses but instead are discharged into the sheet discharge space disposed inside the housing where users can access the sheets externally. The housing-internal discharge space is typically disposed between a scanner and a main body of the image forming apparatus.
In addition, as an approach to make the image forming apparatuses compact, finishers that perform post-processing, for example, aligning, sorting, stapling, and/or punching the output sheets are disposed inside the housing-internal discharge space, in contrast to their conventional disposition on the side of the image forming apparatuses.
For example, one known image forming apparatus includes a movable discharge tray, a discharged-sheet detector, and a discharge tray lift that are disposed within the housing-internal discharge space disposed beneath the scanner. The discharged-sheet detector detects the position of the surface of the sheet discharged on the top on the movable discharge tray, that is, the level of the discharged sheets, and the discharge tray lift moves the movable discharge tray in a direction in which the sheets are stacked. A controller drives the discharge tray lift to adjust the height of the movable discharge tray suitably for the level of the discharged sheets detected by the discharged-sheet detector while maintaining a space between the scanner and the sheets discharged on the movable discharge tray so that the user can remove the sheets therefrom.
In another known image forming apparatus, sheets are discharged through a discharge port disposed on the inner side wall of the main body forming the housing-internal discharge space and are stacked on a first discharge tray integrally formed on an upper surface of the main body that forms a bottom of the housing-internal discharge space. A detachably attachable second tray or finisher such as a stapler can be provided above the discharge tray in the housing-internal discharge space. The discharge tray includes a horizontal portion formed on a downstream side in the direction in which the sheets are discharged (hereinafter “sheet discharge direction”) and a sloped portion continuous with the horizontal portion. The sloped portion descends toward upstream and is lowest at the position under the discharge port. When the second tray or the finisher is mounted in the housing-internal discharge space, it is possible that the leading edge of the sheets discharged onto the sloped portion of the discharge tray may hit the lower surface of the second tray or the finisher and then curve. Therefore, this known image forming apparatus further includes an auxiliary tray detachably attachable to the sloped portion of the discharge tray to adjust the inclination of the sloped portion, thus preventing the sheets from hitting the lower surface of the second tray or the finisher.
Although finishers can be thus mounted in the housing-internal discharge space, if a sheet receiving port of the finisher, through which the sheet output from the image forming apparatus enter the finisher, is not aligned with the discharge port of the image forming apparatus, the apparatus can be jammed and the sheet is thus damaged.
In view of the foregoing, there is a need to position the finisher at a position adjacent to the discharge port of the image forming apparatus so that the sheet receiving port of the finisher is properly connected to the discharge port of the image forming apparatus with a simple mechanism.